Ralph Kahle

After obtaining an aerospace engineering degree from the Technical University of Dresden, Ralph Kahle conducted research as a doctoral student at the DLR Institute of Planetary Research in Berlin on the areas of exposure to near-Earth asteroids and comets, as well as the avoidance of collisions.

Since 2004, he has been a researcher at the German Space Operations Center (GSOC) at DLR Oberpfaffenhofen. He works on flight dynamics systems for satellite missions for communications and Earth observation as well as robotic missions such as the on-orbit servicing mission DEOS.

Ralph Kahle is the flight dynamics engineer for the TerraSAR-X / TanDEM-X Mission. His responsibilities include precise orbit and attitude determination for the satellites, measuring their position relative to one another with millimetric accuracy, the generation of auxiliary products for radar processing, and control of the satellite formation.

Posts from Ralph Kahle

The goal of PRISMA is to demonstrate sensors and flight software needed to perform formation flight and rendezvous missions. With respect to future on-orbit servicing missions, PRISMA is a milestone in developing and demonstrating the required technologies in orbit. The experiment operations started after commissioning and separation of the two spacecraft, Mango and Tango, in August 2010 . The basic experiment programme is planned to last ten months, with an additional two months for an extended campaign. The first half of this timeline was successfully executed by the Swedish Space Corporation, and after the transfer of operations on 14 March it is now GSOC's turn to conclude the nominal first year of operations. Let's have a closer look at the project structure, the experimenter's contributions and the experiment operations to be conducted at GSOC.
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On 14 March 2011, the German Space Operations Center (GSOC) took over operations of PRISMA. Despite my 20 years of service, I must say that even though every mission launch is special, the transfer of operations for an ongoing mission has a very new ‘feel’ about it. PRISMA has been different in many ways. The aim of this mission is to demonstrate various formation flying and rendezvous scenarios at separations of as little as a few metres with satellites Tango and Mango.
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On its launch date, 21 June 2010, roughly 16,000 kilometres separated TanDEM-X from its twin satellite, TerraSAR-X. Now, that distance has shrunk to just 2000 kilometres. The time has come for the relative movement between the two satellites to be slowed down, and for them to be set up for formation flying. To accomplish this, the Flight Dynamics Group at the German Space Operations Center (GSOC) will carry out a total of 10 orbital manoeuvres over the next eight days.
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This place, the German Aerospace Center at DLR Oberpfaffenhofen (close to Munich) has a serious trekkie air. As you walk into the building where the action is tonight, chairs and shiny lights have been set up. This is where the infotainment programme will be streamed live. But take a couple of turns around nondescript corridors, and you’re on the bridge — they actually call it that (hence the trekkie reference).
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With finalisation of the functional tests for the satellite bus and instrument, we have reached another important milestone. Evaluation of the test data confirmed that everything was nominal. In one of the last tests, the satellite was powered up solely by its internal supply and the external power was switched off. This too was successful, so the satellite was turned off and the wiring to the electrical test equipment was removed – a slightly melancholic moment. The next time we receive a signal from the spacecraft it will be in orbit, having separated from the launcher.
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